They would ask me what actors I saw in the roles. I would tell them, and they’d say “Oh that’s interesting.” And that would be the end of it.
--Elmore Leonard, in 2000, on the extent of his input for Hollywood's adaptation of his novels

When I wrote The True History of Merlin the Magician I had no real visual image of Merlin in my mind – how can you tie down someone who ‘lived’ from the 5th century to the 16th, and took the forms of boy-prophet, scholar, doctor, hermit, Welsh warrior-prince and half-demon, to one physical incarnation or appearance? The one thing I was clear about was that the historical Merlin was not the aged sage in a pointy hat seen in Disney’s version.

But, once I started to think about Merlin as a movie, the actor to play Merlin was obviously Johnny Depp. A blend of Edward Scissorhands, Captain Jack Sparrow and The Mad Hatter is about as close to the Merlin of medieval chronicles and prophecies as I can imagine – though adding to these the hermit who can see to the very end of time and understands the secrets of the earth might be a stretch even for Johnny Depp. Of course, since Merlin can change shape, and take on the appearance of any person he chooses, this movie would not need to be restricted to just one lead actor. Yet the versatility of an actor like Johnny Depp is so impressive that it’s a form of magic in its own right, and I think it would help to get across the message that Merlin was truly believed to be a real person.

One of the chapters of the book looks at how Merlin the historical figure became so famous that courtly romance (the equivalent of historical novels, in a way) were written about him and became best sellers. It was these romances which imagined an explanation for Merlin’s disappearance from the histories after he’d brought about the birth of King Arthur. The story was that there were two things even more powerful than Merlin’s magic: love and feminine cunning – and the two were embodied in the character of Viviane. Here is a powerful character, but one who is also a misogynist stereotype. Viviane starts out as a young girl sent to entice the great magician, grows into a powerful enchantress as she learns Merlin’s magic, and ends as a ruthless killer (in some versions at least). I am going to cheat slightly and go for a younger Helen Mirren, in her incarnation as Cleopatra, blending into her role in Prime Suspect. That may sound surprising, but to Viviane, Merlin is a villain.

Finally, the director should be Sam Mendes. It’s not that I think Merlin is an early James Bond (though the fictional Merlin was a Brit who travelled the globe, settling political, diplomatic and even religious crises, so I might be on to something). It’s more that I enjoy the idea of Merlin as a musical, with all the doomed romance of Cabaret.

“Compared to a novel, a film is like an economy pizza where there are no olives, no ham, no anchovies, no mushrooms, and all you’ve got is the dough.”
--Louis de Bernières, author of Captain Corelli’s Mandolin